1. Field of the Invention
The present invention relates to a primer composition that imparts sufficient adhesion to polyurethane base adhesives irrespective of the kind of polyvinyl chloride.
2. Description of the Related Art
When use is made of polyurethane base adhesives on polyvinyl chloride as an adherend, there have heretofore been used primers containing a polyester resin and an isocyanate compound.
However, not all polyurethane base adhesives are compatible with the primers having the above-described composition. Some primers suffer from a decrease in adhesion itself depending on the type of components to be blended in the adhesive and it is difficult to develop sufficient adhesion by use of conventional primers.
On the other hand, polyvinyl chloride, as an adherend, contains various components in order to have various characteristics. However, addition of some components causes a reduction in adhesion with the adhesive. Generally, soft polyvinyl chloride containing a larger amount of plasticizer tends to be more difficult to adhere.
Recently, so-called module glass that comprises window glass used for a car body whose periphery is covered with polyvinyl chloride has been used more and more widely. Therefore, there has been a keen demand for a primer that allows polyurethane base adhesives to exhibit excellent adhesion to polyvinyl chloride as an adherend in bonding modular glass with other elements.